The invention relates to a vehicle brake vibration damper, to a brake piston and to a brake comprising such a damper.
In a vehicle equipped with disk brakes, each wheel that has to be retarded by a braking system such as this comprises a brake disk secured to the wheel and a braking device secured to the chassis of the vehicle and which, through friction, slows the rotational movement of the disk.
The braking device comprises, on each side of the brake disk, a brake pad borne by a backing plate. Each backing plate is able to move at right angles to the plane of the disk and is guided at both ends in housings in a yoke.
The command to apply braking is transmitted in the known way by a hydraulic circuit filled with a brake fluid. A braking control, generally located at the driving position allows action on a system of pistons so that the braking effort can be transmitted to the brake pads via the brake fluid.
The brake pads work by rubbing brake linings against the brake disk and, during braking, tightly grip the disk and slow the rotation thereof.
However, when the brake linings such as the brake pads come into contact with a rotary member secured to an axle of the vehicle, such as a brake disk, and when this rotary member is slowed, vibrations may arise. These vibrations are more noticeable and annoying under moderate braking than under heavy sudden braking because moderate braking often lasts for longer, is employed more frequently, and the driver of the vehicle is generally more attentive to how his vehicle is behaving and to the noise being made. Furthermore, moderate braking generally occurs at low speed when the vehicle is often less noisy and the noise of vibration due to braking is far more noticeable.
In spite of attempts made to limit these vibrations, experience shows that these cannot be eliminated and that, in any event, as the vehicle ages and its parts become worn, there will always be the risk of vibrations.
One solution is therefore to damp these vibrations and the acoustic frequencies they generate throughout the vehicle.
The invention therefore provides measures for damping these vibrations.
The invention therefore relates to a disk brake vibration damper which comprises a piston intended to apply an axial braking pressure to a brake pad. The damper according to the invention comprises a cylindrical element equipped on its cylindrical peripheral surface with a layer of a supple material which exhibits good properties of adhesion with the material of the piston and with the material of said cylindrical element. Said cylindrical element is intended to be positioned inside an axial cavity of the piston with said layer of supple material in contact with the interior wall of the cavity of the piston.
Advantageously, said layer of supple material is made of a viscous material.
According to one embodiment, the layer of viscous material is made of a viscoelastic material.
According to one nonlimiting embodiment, provision will be made for said cylindrical element to be a cylindrical ring.
According to another embodiment of the invention, the cylindrical element slides in said cavity of the piston and hermetically seals this cavity.
Advantageously, said cylindrical element is made of a metallic material.
As an alternative, provision may just as easily be made for said cylindrical element to be made of a plastic.
The invention also relates to a brake piston using the damper thus described.
The invention also relates to a vehicle disk brake applying this brake piston fitted with this damper.